“One asks oneself if he is in the realms of the fashion industry at all? Or a dinosaur sat atop an ivory tower with no access to Instagram or any street-style blogs,” the Fashion Features Director of British Vogue wrote in The Telegraph UK.

“To cast such trite aspersions is like saying that women can’t have long hair the other side of 40, or that a 57-year-old man can’t have a blond, flowing, tonged (?), highlighted (?), backcombed (!) bouffant, whether they’re a celebrity hairdresser or otherwise.”

Harris is speaking from experience. Not only has her grey hair become a trademark, but she’s been joined by a legion of stylish women embracing a paler shade of pewter.

From Helen Mirren to model Kristen McMenamy - who is perhaps more famous now than she was with her deep red mane - a new generation is embracing the march of time. A number of others, including Cara Delevingne, Kate Moss, Jourdan Dunn and runway favourite Marga Esquivel are faking it with the help of a colourist.

“So often I have young girls come up to me in the street and they’re like, 'Who’s your hairdresser? What dye do you use?’” says Harris, who started turning grey naturally at the age of 16.

L-R: Model Marga Esquivel's grey hair has made her a favoruite of Gucci; Sarah Harris's grey mane stands out in a crowd. Both images via Instagram.

Whether you’re faking it or going au naturel, here’s everything you need to know to be a silver fox.

Blend

Most colourists recommend waiting until you’re at least 60% grey before committing to the shade.

During the awkward growing out phase, you could also try also try asking a colourist to add some highlights or lowlights to better blend the grey with pigmented hair, or try using a temporary cover up.

Tone

Once a week, use a toning shampoo designed to counteract any brassiness. Like blonde, grey hair is more porous and prone to discolouration from environmental pollutants like chlorine, so a toner will ensure you maintain a nice shade of steel. (Don’t overuse, unless you’re keen on a light blue tint.)

When hair turns grey, the cuticle thins out, which can leave strands coarse, dry or prone to breaking. Use a moisturising shampoo and conditioner to keep hair looking healthy, and consider a deep moisture treatment once a week.